Windows 7 PC sign-in to Windows 2000 Server no longer working
I have been using Win7 on my Dell Precision M6400 laptop for a couple of months without problems (including connecting to our W2K server without issue) till last night - since then the Win2K Server won't accept any login from my Win7 laptop. I can access the internet and I can access other PC's (using WinXP) on our network and I can access the Win2K Server from my laptop using pcAnywhere as usual, but I can no longer log in to use the Server's drives! Other users (all using WinXP) are not affected. In trying to fix the problem (in case the password had got scrambled), I have reset the password on the Server to ensure it is identical to what I am entering on my laptop but to no avail. After a few attempts I get locked out and have to reset the lockout on the Server. I have rebooted the Server (once), and have rebooted my laptop multiple times to ensure it's not something transient. I have tried logging in as a different user, I have also tried mapping a drive using NET USE ... always the same response: "Login failure: unknown user name or bad password". Since the user name eventually gets locked out, that is correct. Since I reset the password to something simple temporarily to ensure no typos (and no CAPS lock is not on), the password I type is guaranteed to be correct. I also tried suppressing the password. All to no avail.
Obviously something has changed but I have no idea what. Nothing was being done on the Win2K Server (nor has anything been done for months and of course it has had no Windows Updates for 2 years), so presumably it is not the Server itself at fault. On my Win7 laptop, just before the problem started, I had a problem with connecting an e-Sata drive and had to do a System Restore to 24 hours before (which took out the latest Win Update, which seems totally unrelated - after all, everything worked fine up to and for 12 hours after the Win Upgrade). But somehow something must have got changed! But what?
I spent 2 hours on the phone with Dell this morning and checked all the hardware (with their diagnostics) and BIOS settings, and checked some software settings but to no avail. Since Win 7 wasn't provided by Dell (it is a genuine Win 7 downloaded from MS - we had an MSDN subscription at the time), the support guy was reluctant to help with software settings (so in desperation I have asked for a quote for a Dell copy of Win 7 configured for the M6400, if that's the only way to get their help to fix this problem).
I worked on this for several hours last night and all day today (trawling the web, trying alternatives) but can't find any way of fixing it. It is as though the laptop has suddenly decided of its own accord to encrypt the passwords sent to the Server in a way the Server doesn't understand, but I can't find anything in the Registry that corresponds to anything I have found on the web.
Has anyone seen such a thing before, or have any idea what else I can try, please?